{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,16]],"date-time":"2025-12-16T12:51:08Z","timestamp":1765889468241,"version":"3.37.3"},"reference-count":38,"publisher":"Georg Thieme Verlag KG","issue":"01","license":[{"start":{"date-parts":[[2025,2,24]],"date-time":"2025-02-24T00:00:00Z","timestamp":1740355200000},"content-version":"vor","delay-in-days":54,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Arq Neuropsiquiatr"],"published-print":{"date-parts":[[2025,1]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>\n          Background\u2003Long coronavirus disease (long COVID, LC) is defined as the continuation or development of new symptoms 3 months after the acute stage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In LC, the rate of fatigue\/postexertional malaise (F-PEM) has been described to be as high as 70%, regardless of age or severity of the acute symptoms.<\/jats:p><jats:p>\n          Objective\u2003To evaluate the neuromuscular junction (NMJ) function and the isolated muscle fiber conduction velocity (MFCV) in situ in LC cases and controls.<\/jats:p><jats:p>\n          Methods\u2003We studied 37 subjects without SARS-CoV-2 (controls) and 32 cases of SARS-CoV-2 infection, half with LC symptoms (LC-yes) and half without them (LC-no). Single-fiber electromyography (jitter measured with a concentric electrode), MFCV, the fast-to-slow MFCV ratio (F\/S ratio), and the motor unit potentials (MUPs) were taken in the tibialis anterior muscle.<\/jats:p><jats:p>\n          Results\u2003At least 1 jitter parameter was abnormal in 1\/37 controls, in 1\/16 LC-no patients, and in 2\/16 LC-yes patients, without significant differences among them. None of the subjects with abnormal jitter presented fluctuation symptoms or positive acetylcholine-receptor antibody. The MFCV and F\/S ratios did not show abnormalities in any of the participants. The MUPs did not show myopathic or neurogenic abnormality in needle electromyography. The most frequent symptom in LC was F-PEM, which occurred in all LC-yes patients and was significantly different from the other groups.<\/jats:p><jats:p>\n          Conclusion\u2003Fatigue\/postexertional malaise was found in all cases of LC, and the electrophysiological findings did not indicate the muscle fiber or the NMJ as a relevant factor in this condition.<\/jats:p>","DOI":"10.1055\/s-0045-1802961","type":"journal-article","created":{"date-parts":[[2025,2,25]],"date-time":"2025-02-25T00:16:43Z","timestamp":1740442603000},"page":"001-008","source":"Crossref","is-referenced-by-count":2,"title":["Jitter and muscle fiber conduction velocity in long COVID fatigue"],"prefix":"10.1055","volume":"83","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9384-9964","authenticated-orcid":false,"given":"Jo\u00e3o Aris","family":"Kouyoumdjian","sequence":"additional","affiliation":[{"name":"Faculdade Estadual de Medicina de S\u00e3o Jos\u00e9 do Rio Preto (FAMERP), Departamento de Ci\u00eancias Neurol\u00f3gicas, Psiquiatria e Psicologia M\u00e9dica, Laborat\u00f3rio de Investiga\u00e7\u00e3o Neuromuscular, S\u00e3o Jos\u00e9 do Rio Preto SP, Brazil."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-5915-2030","authenticated-orcid":false,"given":"Leticia Akemi Rama","family":"Yamamoto","sequence":"additional","affiliation":[{"name":"Faculdade Estadual de Medicina de S\u00e3o Jos\u00e9 do Rio Preto (FAMERP), Departamento de Ci\u00eancias Neurol\u00f3gicas, Psiquiatria e Psicologia M\u00e9dica, Laborat\u00f3rio de Investiga\u00e7\u00e3o Neuromuscular, S\u00e3o Jos\u00e9 do Rio Preto SP, Brazil."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3818-168X","authenticated-orcid":false,"given":"Carla Renata","family":"Graca","sequence":"additional","affiliation":[{"name":"Faculdade Estadual de Medicina de S\u00e3o Jos\u00e9 do Rio Preto (FAMERP), Departamento de Ci\u00eancias Neurol\u00f3gicas, Psiquiatria e Psicologia M\u00e9dica, Laborat\u00f3rio de Investiga\u00e7\u00e3o Neuromuscular, S\u00e3o Jos\u00e9 do Rio Preto SP, Brazil."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"194","published-online":{"date-parts":[[2025,2,24]]},"reference":[{"issue":"08","key":"ref1","doi-asserted-by":"publisher","first-page":"727","DOI":"10.1056\/NEJMoa2001017","article-title":"A Novel Coronavirus from Patients with Pneumonia in China, 2019","volume":"382","author":"N Zhu","year":"2020","journal-title":"N Engl J Med"},{"issue":"03","key":"ref3","doi-asserted-by":"publisher","first-page":"133","DOI":"10.1038\/s41579-022-00846-2","article-title":"Long COVID: major findings, mechanisms and recommendations","volume":"21","author":"H E Davis","year":"2023","journal-title":"Nat Rev Microbiol"},{"issue":"10","key":"ref5","doi-asserted-by":"publisher","first-page":"737","DOI":"10.1080\/23744235.2021.1924397","article-title":"Long COVID or post-COVID-19 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Tankisi","year":"2023","journal-title":"Clin Neurophysiol Pract"},{"issue":"08","key":"ref39","doi-asserted-by":"publisher","first-page":"1974","DOI":"10.1016\/j.clinph.2021.04.009","article-title":"Myopathic changes in patients with long-term fatigue after COVID-19","volume":"132","author":"J Agergaard","year":"2021","journal-title":"Clin Neurophysiol"},{"key":"ref40","doi-asserted-by":"publisher","first-page":"65","DOI":"10.1016\/j.clinph.2023.01.010","article-title":"Myopathy as a cause of Long COVID fatigue: Evidence from quantitative and single fiber EMG and muscle histopathology","volume":"148","author":"J Agergaard","year":"2023","journal-title":"Clin Neurophysiol"}],"container-title":["Arquivos de 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